FIELD EFFECT TRANSISTOR AND METHOD FOR MANUFACTURING SAME

摘要

A field effect transistor is characterized by comprising a semiconductor layer projecting upward from a flat surface of a base, a gate electrode arranged on both lateral surfaces of the semiconductor layer, a gate insulating film interposed between the gate electrode and each lateral surface of the semiconductor layer, and source/drain regions wherein an impurity of a first conductivity type is introduced. The field effect transistor is further characterized in that the semiconductor layer has a channel-forming region in a portion between the source region and drain region and the upper part of the semiconductor layer in the channel-forming region has a channel impurity concentration adjusting region wherein the concentration of an impurity of a second conductivity type is higher than the lower part. The field effect transistor is still further characterized in that when in operation and a signal voltage is applied to the gate electrode, a channel is formed in a lateral surface portion of the semiconductor layer in the channel impurity concentration adjusting region which portion is opposite to the gate insulating film.